Do you know solar water pump？

1. Definition and composition

1.1 Core definition

solar water pumping system (SWPS) is a device that converts solar energy into electricity to drive water pumps to pump water without relying on traditional power grids or fossil fuels.

1.2 System composition

Solar cell array

Type: monocrystalline silicon (efficiency 18%-22%), polycrystalline silicon (15%-18%), thin film (10%-13%).

Power matching: Designed according to the pump power and sunshine conditions, such as a 1kW pump needs to match a 1.5-2kW photovoltaic panel (considering losses).

Support structure: fixed/tracking (single-axis/double-axis), the latter increases power generation by 10%-30%.

Water pump

DC pump:

Submersible pump (for deep wells): corrosion-resistant material, working depth up to 200 meters.

Centrifugal pump (surface water): low head (<50 meters), large flow (5-100m³/h).

AC pump: An inverter (such as a sine wave inverter) is required, suitable for high power (>5kW) scenarios.

Controller

Function: MPPT (maximum power point tracking) controller (efficiency improvement of 20%-30%), overvoltage/undervoltage protection, soft start.

Additional modules: water level sensor (to prevent dry pumping), Bluetooth/WiFi remote monitoring.

Energy storage system (optional)

Battery type: lead-acid battery (low cost), lithium battery (long life, charging and discharging efficiency>95%).

Capacity calculation: to meet the needs of 1-3 days of rainy days, for example, a 10kWh battery (50% discharge depth) is required for a daily power consumption of 5kWh.

Auxiliary equipment

Filter: to prevent clogging with sediment, such as a stainless steel mesh filter (mesh number ≥80).

Pipeline: PVC (low cost), HDPE (UV-resistant, life of 20 years).

2. Working principle and process

2.1 Energy conversion process

Light energy → DC: Photovoltaic panels generate electron-hole pairs through PN junctions and output DC voltage (such as 36V, 48V).

Electric energy regulation: MPPT controller dynamically adjusts voltage and current to maximize the output power of photovoltaic panels.

Driving water pump:

DC motor: directly powered by photovoltaic panels, efficiency > 90%.

AC motor: inverter converts DC to AC (such as 220V/380V), efficiency 85%-92%.

2.2 System operation mode

Direct drive: no energy storage, working during sunshine, shutdown on cloudy days (suitable for non-continuous needs such as irrigation).

Energy storage buffer: batteries smooth power fluctuations and achieve 24-hour water supply (suitable for household water use).

3. Classification

By current type

By pump structure

Submersible pump:

Deep well submersible pump: head 50-200 meters, stainless steel shell, cable waterproof grade IP68.

Shallow well submersible pump: head <50 meters, flow rate 1-10m³/h, suitable for rivers and ponds.

Centrifugal pump:

Self-priming: can automatically exhaust, suitable for intermittent pumping of surface water.

Multistage centrifugal pump: high head (100-500 meters), used for water delivery in mountainous areas.

By system scale

Small system (<1kW): household water, small vegetable garden irrigation, daily water supply 1-5m³.

Medium system (1-10kW): farm irrigation, village centralized water supply, daily water supply 10-100m³.

Large system (>10kW): desert greening, industrial water supply, daily water supply >200m³.

4. Application scenarios and cases

4.1 Typical scenarios

Agricultural irrigation:

Case: A 5kW system pumps 50m³ of water per day on a farm in Rajasthan, India, irrigating 10 hectares of drought-resistant crops.

Technical points: The drip irrigation system is equipped with a pressure-compensated sprinkler, saving 30% water.

Household water supply:

Case: In sub-Saharan Africa, 300W system + 2kWh battery can meet the daily water consumption of 200L for a family of 5.

Technical points: Equipped with UV sterilization module to ensure the safety of drinking water.

4.2 Special scenarios

High altitude areas: Low temperature resistant photovoltaic panels (-40℃ operation) are required, and the insulation level of the water pump motor is H level.

Seawater desalination: With reverse osmosis membrane (RO), system power > 10kW, water production cost is about 0.5-1 US dollars/m³.

5. Technology selection and design

5.1 Calculation of key parameters

Head (H):

Formula: H = vertical height + pipeline friction loss (every 10 meters of horizontal pipe ≈ 1 meter of head) + outlet pressure requirement.

Example: Well depth 30 meters, horizontal pipe 100 meters (friction loss 10 meters), total head H=30+10=40 meters.

Flow (Q):

Formula: Q = daily water demand (m³) / effective sunshine hours (h).

Example: 20m³ of water is required daily, 5 hours of sunshine, then Q=4m³/h.

PV power (P):

Formula: P = (Q × H × 0.163) / (peak sunshine hours × system efficiency (0.4-0.6)).

Example: Q=4m³/h, H=40 meters, 5 hours of sunshine, efficiency 0.5 → P≈ (4×40×0.163)/(5×0.5)=10.4kW.

5.2 Configuration example

Demand: irrigate 5 mu of orchard, daily water demand 15m³, head 30 meters, 4 hours of sunshine.

Solution:

Water pump: 1.5kW DC submersible pump (Q=3.75m³/h, H=30m).

Photovoltaic panel: 3kW monocrystalline array (6×500W panels).

Controller: MPPT 48V/30A.

Energy storage: No battery required (pump water directly to high-level water tank during the day).

6. Installation and maintenance

Installation details

Photovoltaic panel inclination:

Fixed: latitude ±10° (such as 40°N in Beijing, inclination 30°-50°).

Seasonal adjustment: +15° in winter, -15° in summer.

Pipeline layout:

Avoid right-angle elbows, use 45° elbows to reduce friction losses.

Surface pipelines need to be UV-proof (HDPE pipes) or buried at a depth of >0.5 meters to prevent freezing.